1925 Cadillac V63 - Heating Trouble

This one runs a bit hot on the right bank- Testing with a temp-gun I see the back two cylinders run 20 degrees hotter than all other cylinders. Water pumps SEEM to both flow about the same- Water temp return on both sides close (the right will be hotter of course) Engine runs smooth- No bubbles in radiator, no water in oil. ONE HINT: Removal of spark plugs from the right bank, ALL of them were a bit sticky on removal (had to use the wrench because threads were gummy)--- Left bank all plugs came out by hand. Compression test was good--

I am told that this engine had been rebuilt when the car was restored- BUT there were some "problems" with the right bank. No one can tell me what those problems were..

Are there more than one head gasket set for these? Could there be a miss-matched head and block on the right side? Is it possible to mix up type 61 cylinders or head? Or some of the differences from 24 to late 26-early27? Ideas?

I have read somewhere these engines have oil circulation problems: even plugging of some of the oil passageways. Could this cause local overheating? Mike Barnes, Vancouver, B.C.

Check out the early V-8 Cadillac group, it's a yahoo group, for advice.